In an impact event, “submarining” occurs when a seat occupant is forced underneath their seatbelt, which can cause severe injuries. The submarining effect can generally be mitigated with proper seat occupant restraint and augmented seat frame design. In a vehicle with moving seats which are not limited to a single location or orientation, such as within an autonomous vehicle, extra care needs to be taken to prevent submarining. Thus, a vehicle seat assembly having safety features configured to prevent submarining is desired, wherein the safety features are fully integrated into the seat assembly design, such that the safety features properly operate without regard to the location or orientation of the vehicle seat assembly within a vehicle.